1. Field of the Invention
This invention relates to a plasma etching apparatus, and more particularly to a plasma processing apparatus such as a plasma CVD apparatus.
2. Description of the Related Art
There has been known a magnetron plasma etching apparatuses in which a pair of electrodes are arranged in an opposed relationship in a process chamber, an article to be processed is loaded on one of the opposed electrodes, plasma is generated between the opposed electrodes by means of high frequency current, a magnetic field which is perpendicular to an electric field is formed in parallel with the article to be processed and etching is performed on the article.
In this kind of magnetron plasma etching apparatus, it is necessary to generate a magnetic field in a range larger than the surface area of an article to be processed such that a uniform magnetic field is formed in parallel with articles to be processed. In consequence, needless discharge is likely to occur at the corner portions which form recesses when the process chamber assumes a parallelepiped form.
The state of the plasma in the process chamber must be externally monitored in the magnetron plasma etching apparatus. In doing so, a notch is formed in the inner wall of the process chamber and is covered with a transparent member to be used as a plasma monitoring window. The notch forms a depression and thus produces needless discharge.
Further, depressions are also formed by gates for opening and closing transportation paths, opened to the process chamber, for transporting an article to be processed into or out of the process chamber. This structure creates needless discharge.
These problems arise not only in the magnetron plasma etching apparatuses but also in other plasma etching apparatuses in which no magnetic field is generated.